Detection of endotoxins and bacterial agents in collected blood bags and their recipients

Bacterial contamination of blood and its cellular components remains an unresolved problem in transfusion medicine, and is considered to be the most common microbiological cause of transfusion associated morbidity and mortality. This is because contaminated units may contain large numbers of virulent bacteria as well as, endotoxins that are considered to be fatal to the recipients. Endotoxins are high-molecular weight complexes of lipopolysaccharides that constitute the major cell wall component in all Gram-negative bacterial families. These molecules have been intensively investigated because of the increasing appreciation of their potentially pathogenic role in a wide variety of human disease states. The present study aimed to detect endotoxins and bacterial agents in collected blood bags and their transmission to the recipients of these blood bags. The study involved 100 randomly selected blood bags and their recipients. They were all examined by Limulus Amebocyte Lysate [LAL] assay using gel clot method for detection of endotoxins and by blood culture for the detection of bacterial agents. Endotoxins were detected in five blood bags [5%] using LAL assay [gel clot method], while bacterial contamination was found in only one blood bag. The bag that gave positive blood culture yielded Staphylococcus aureus, which was mostly a skin associated organism and was considered as a contaminant related to the procedure during donor venipuncture. None of the 100 studied recipients of these blood bags revealed positive blood culture. It was concluded from this study that LAL assay is a rapid, easy to perform, and a highly sensitive test that can detect as little as 0.03 endotoxin units per ml using the gel-clot method. In addition not all endotoxins or bacterial agents could be transmitted to the recipients of blood bags, this depends on their volume and whether the recipient is on antibiotic therapy or not

Long-term immunogenicity and efficacy of a recombinant hepatitis B vaccine in Egyptian children

In 1992, Egypt adopted a hepatitis B vaccine schedule at 2, 4 and 6 months of age. We evaluated the long-term immunogenicity and efficacy of vaccination using this schedule in 180 children whose time lapse since last vaccination varied between 1 month and 5 years. None of the participants had clinical hepatitis, HBsAg was not detected in any participant and all but one had negative results for anti-HBc test. Although a high seroprotection rate [93.3%] was elicited 1 month after vaccination, there were low initial anti-HBs concentrations and both declined rapidly over time. Thus, the short interval [2 months] between the second and third doses of vaccine is less desirable in the long term. We recommend booster inoculations for all previously vaccinated children and a new vaccination schedule at 1, 2 and 9 months